Robotic rolling vehicle apparatus and method

ABSTRACT

A robotic vehicle having a body with an internal volume. A plurality of extendable legs project outwardly from the body for supporting the body on a surface and for propelling the body, in at least a partial rolling motion, over the surface. A gimbal system is supported within the body. The gimbal system has a support platform that is moveable within at least two non-parallel planes. An actuator is supported on the support platform and is positionable by the gimbal system into different positions to actuate selected ones of the extendable legs, to thus assist in propelling the vehicle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is generally related in subject matter to U.S. Pat. No.7,165,637, entitled “Robotic All Terrain Surveyor”, to M. Tanielian,issued Jan. 23, 2007, and assigned The Boeing Company, and also to U.S.divisional patent application Ser. No. 11/538,182 filed Oct. 3, 2005,now U.S. Pat. No. 7,434,638, which is a divisional of application Ser.No. 10/981,912 filed Nov. 4, 2004 now U.S. Pat. No. 7,165,637. Both arehereby incorporated by reference into the present disclosure.

FIELD

The present disclosure relates to vehicles, and more particularly to apropulsion system for a robotic vehicle that enables the vehicle totraverse a ground surface.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Interest in robotic vehicles continues to increase. Examples of roboticvehicles are disclosed in U.S. Pat. No. 7,165,637, entitled “Robotic AllTerrain Surveyor”, to Tanielian, issued Jan. 23, 2007, and U.S. PatentPublication No. 2007/0144798, published Jun. 28, 2007, which is adivisional application of U.S. Pat. No. 7,165,637. Both of thesereferences are owned by The Boeing Company, and both are herebyincorporated by reference into the present application.

With any form of robotic vehicle, the vehicle's overall weight andmechanical complexity are factors that designers generally seek tominimize. For example, with the robotic surveyor of U.S. Pat. No.7,165,637, the device includes a plurality of legs that can be extendedto help propel the device in a general rolling motion along a desiredcourse. A plurality of actuators may be included to accomplish this,with one actuator being associated with each leg. Thus, if six legs areused, then a minimum of six actuators may be employed; if twelve legsare used then twelve actuators may be employed and so on.

SUMMARY

The present system and method relates to a robotic vehicle that may bemade lighter and with fewer electromechanical components than previouslydeveloped robotic vehicles.

In one embodiment the vehicle comprises a body defining an internalvolume. A plurality of extendable legs project outwardly from the bodyfor supporting the body on a surface and for propelling the body, in atleast a partial rolling motion, over the surface. A gimbal systemsupported within the body has a support platform that is moveable withinat least two non-parallel planes. An actuator is supported on thesupport platform. The actuator can be positioned by the gimbal systemsuch that the actuator can be moved into different positions to actuateselected ones of the extendable legs to assist in propelling thevehicle.

In one specific embodiment the body forms a sphere. In anotherembodiment the body forms a polyhedron. In these embodiments theextendable legs may be arranged so that a coaxial center line of eachleg intersects the geometric center of the body. The gimbal system isused to axially align the actuator with the particular leg to beextended, and then the actuator is actuated which causes the selectedleg to extend. The extendable legs each may have a spring that returnsthe leg to its retracted position when the leg is not being engaged bythe actuator. By actuating specific ones of the extendable legs incertain sequences, a general rolling motion of the body may be achieved.

In another specific embodiment the actuator may comprise anelectromechanical solenoid type actuator that is controlled by acontroller. The controller may be located within the body. Thecontroller may be powered by a suitable compact battery or other powersource that is also carried within the body of the vehicle.

Methods for forming a robotic vehicle and for propelling a vehicle arealso described.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a perspective view of one embodiment of a robotic vehicle ofthe present disclosure;

FIG. 2 is 2D representation of the vehicle similar to a cross sectionalplan view in accordance with section line 2-2 in FIG. 1, of the interiorarea of the body of the vehicle of FIG. 1 showing a gimbal system andthe actuator supported on a gimbal system;

FIG. 3 is a partial side view of the vehicle in FIG. 2 taken inaccordance with directional line 3-3 in FIG. 2, and showing a gimbalsystem and actuator from the side;

FIG. 4 is a simplified electrical block diagram illustrating majorelectrical and electromechanical components of the vehicle of FIG. 1;

FIGS. 5A-5D illustrates a sequence where the actuator is moved intoalignment with different ones of the extendable legs so that a generalrolling motion can be imparted to the vehicle;

FIG. 6 is a flowchart illustrating several operations performed incausing motion of the vehicle of FIG. 1;

FIG. 7 is another embodiment of the vehicle in which pivoted legs areused to transmit thrust from the centrally mounted actuator to theground; and

FIGS. 8A and 8B show perspective views of other embodiments of thevehicle that employ polyhedron shaped bodies.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

Referring to FIG. 1, there is shown a robotic vehicle 10 in accordancewith one embodiment of the present disclosure. The vehicle 10 in thisembodiment includes a spherically shaped body 12 having a plurality oflinearly extendable legs 14 supported from, and extending from, the body12. The legs 14 are further arranged such that a coaxial center line ofeach leg 14 extends through the geometric center of the body 12. Thelegs 14 may each be constructed as telescoping assemblies where atelescoping end portion 14 ₁ moves relative to a fixed portion 14 ₂ thatis fixedly supported from the body 12.

Referring to FIGS. 2 and 3, the vehicle 10 can be seen to include avolume 16 within the body 12 defined by an interior surface 12 a of thebody 12. Mounted within the body 12 is two-axis gimbal system 18 havinga support platform 20. Mounted on the support platform 20 is an actuator22. In one form the actuator 22 may comprise an electromechanicalsolenoid actuator having a linearly extendable and retractable rod 24.In an alternative form the actuator 22 could comprise a linear motionservo motor, a threaded screw drive, air cylinder, or any suitablecomponent able to move an element linearly into contact with an alignedone of the legs 14.

In FIG. 2, the gimbal system 18 can be seen to include an X-axis servomotor 26, which has an output shaft 26 a connected to the supportplatform 20 In FIG. 3, the gimbal system 18 also can be seen to includea Y-axis servo motor 28 which has its own output shaft 28 a. The servomotors 26 and 28 are supported from a frame element 30 that is pivotallymounted at portions 32 of the frame element 30, in part by the servooutput shaft 26 a, to enable pivoting movement about a first (or “X”)axis 34, and also about a second (or “Y”) axis 36. Thus, the gimbalsystem 18, and particularly the servo motors 26 and 28, can be used toposition the actuator 22 in a plurality of different non-parallelplanes. More particularly, the gimbal system 18 can be used to positionthe rod 24 of the actuator 22 in longitudinal alignment with the coaxialcenter line of any one of the extendable legs 14.

When the actuator 22 is actuated by a suitable signal (typically anelectrical signal), the rod 24 is extended. The actuator 22 may bedesigned such that the rod 24 is retracted automatically (for example byan internal spring) when the electrical signal is removed from theactuator 22. Alternatively, the rod 24 may be retracted via a differentelectrical signal applied to the actuator 22, for example a signal ofdifferent polarity from that used to extend the rod 24. Botharrangements are viewed as being within the purview of the presentdisclosure. The rate of extension and/or retraction of the rod 24 (e.g.,centimeters per second) can be tailored through selection of variousmechanical properties of the actuator as well as through tailoring ofthe electrical signal (e.g., magnitude, frequency, duty cycle, etc.)applied to the actuator 22.

With further reference to FIG. 2, each extendable leg 14 includes abiasing element 38 that is captured between the internal surface 12 a ofthe body 12 and a shoulder 40 of each extendable leg. The biasingelement 38 in this example is a coil spring, but it will be appreciatedthat other forms of biasing elements (e.g., leaf springs) could besubstituted for use as well with only minor modifications to thestructure of the extendable legs 14.

In FIGS. 2 and 3, while the X-axis servo motor 26 is shown supportedoutside of the body 12, it will be appreciated that it could just asreadily be supported within the body if desired. This could beaccomplished by suitable bracing, mounting struts or other likestructure disposed within the volume 16 inside the body 12 that enablesthe gimbal frame element 30 to rotate about the X-axis 34.

Referring briefly to FIG. 4, a block diagram of a control scheme forcontrolling the gimbal system 18 is shown. An electronic controller 42,for example a programmable controller, a microprocessor ormicrocontroller, may be used to generate the electrical signals neededto control the X-axis servo motor 26 and the Y-axis servo 28 motor. Thecontroller 42 may also be used to generate the signals needed to extendand retract then rod 24 of the actuator 22, or alternatively a separatecontroller (not shown) could be used to perform this task. In oneembodiment, the controller 42 provides power to the solenoid actuator 22by discharging a capacitor bank 45 through a relay 46. It will beappreciated that, while not shown, suitable amplifiers will typicallyalso be used and controlled by the controller 42 to generate the neededdrive signals for the X-axis and Y-axis servo motors 26 and 28,respectively. A battery 44 may be used to power the controller 42 and toprovide the current needed to generate the drive signals for the X-axisand Y-axis servo motors 26 and 28. Optionally, the controller 42 may beinterfaced with a miniature RF receiver or transceiver (not shown)housed within the body 12 to enable an external (i.e., remotely located)control system to control operation of the vehicle 10.

Referring to FIGS. 5A-5D, operation of the vehicle 10 will be described.For example, if motion in the general direction of arrow 50 is desired,then leg 14 a will need to be actuated, as this leg presently one of thelegs 14 supporting the vehicle 10 on a ground surface 52. The gimbalsystem 18 is controlled to align the actuator 22 with the coaxial centerline of leg 14 a, as shown in FIG. 5B. The actuator 22 is then actuatedby the controller 42 which causes rod 24 to extend. This extendingmovement enables the rod 24 to extend portion 14 ₁ of actuator 14 a,which imparts a rolling motion to the vehicle 10. The impulse providedby the rapid extension of the actuator rod 24 should be sufficient tocause the body 12 of the vehicle 10 to roll over the immediatelyadjacent leg (in this example leg 14 b) along the generally desired pathof travel. It will be appreciated that by “generally” desired path oftravel, it is meant that the vehicle 10 will have somewhat of aside-to-side travel, or what could be viewed as a general “zig-zag” pathof travel, as it moves in a given direction.

In FIG. 5D, the body 12 is now supported by at least legs 14 b and 14 c,but typically at least one additional leg (not shown in FIGS. 5A-5B)will be arranged so that the body 12 is supported by three of the legs14 when at rest. Continued movement in the general direction of arrow 50would next require extension of leg 14 b. The actuator 22 would then berepositioned by the controller 42 using the gimbal system 18 tocoaxially align the actuator rod 24 with leg 14 b, and theabove-described operation of extending and retracting the rod 24 wouldbe repeated.

The motion sequence in FIGS. 5A-5D produces one type of rollinglocomotion, but others are also possible with this type of actuation.For example, if the leg actuator is capable of higher thrust (due tohigher velocity motion of the extension rod 24), then a hopping type oflocomotion can be produced.

FIG. 6 illustrates a flowchart 100 illustrating operations forcontrolling motion of the vehicle 10. At operation 101, a high leveldecision is made by an autonomous planner or human operator as to thedesired direction of travel. At operation 102, the controller 42determines which leg 14 needs to be actuated to propel the vehicle 10 inthe desired direction. At operation 104 the controller 42 generates theneeded electrical signals to drive the X-axis servo motor 26 and theY-axis servo motor 28 so that the actuator 22 is positioned in axialalignment with the leg 14 to be actuated. At operation 106 thecontroller 42 then generates the required electrical signal to actuatethe actuator 22 and extend the rod 24, thus causing extension of theselected leg 14. At operation 108, the controller 42 maintains theselected leg 14 actuated (i.e., maintains the rod 24 extended) for apredetermined time period, which is typically less than 1 second. Thebody 12 of the vehicle 10 will roll to a new position as the selectedleg 14 is fully extended.

At operation 110, after the predetermined time period expires, thecontroller 42 removes the electrical signal from the actuator 22 toenable the rod 24 of the actuator 22 to be retracted, and thus to enablethe extendable portion 14 ₁ of the selected leg 14 to be retracted byits associated coil spring 38. At operation 112 the controller 42determines if further travel of the vehicle 10 is desired and, if not,the sequence of operation terminates. If operation 112 determines thatfurther travel of the vehicle 10 is required, then a loop is made backto operation 102, and operations 102-112 are repeated. Again, it will beappreciated that as different ones of the legs 14 are actuated, the thatthe vehicle 10 will be propelled in the desired direction (albeit in asomewhat zig-zag fashion). Suitable software or firmware may be includedfor use with the controller 24 to monitor the position of the body 12relative to the ground surface 52, and to determine precisely which leg14 needs to be actuated next to propel the vehicle 10 in the desireddirection. Obviously, any suitable orientation/attitude sensing systemmay be used in connection with the controller 42 to continuously monitorthe orientation of the body 12 relative to the ground surface 52 so thatthe controller may determine exactly which leg 14 needs to be extendednext to effect (or continue) motion of the vehicle 10 in the desireddirection. Determination of which legs are in contact can performed byanalyzing the state of contact switches that may be attached to the feetof the extension legs. Other options include using sensors that candetermine the angular orientation of the vehicle; these types of sensorsmay include inclinometers (such as the dual-axis inclinometers made byVTI Technologies of Dearborn, Mich.) or inertial measurement units (suchas the IMUs made by Cloud Cap Technology, Inc. of Hood River, Oreg.).

FIG. 7 illustrates an alternate embodiment of the vehicle. In thisembodiment (vehicle 11), the legs 15 extend from the body by pivotingabout hinge 17, instead of telescoping. Each leg element consists of aninternal transfer element 39 rigidly connected to an external extensionelement 41, which makes contact with the ground. Each leg 15 is returnedor held in the retracted position by a torsional spring 37. The methodof actuation and locomotion is the same as that of the telescopic legembodiment of the vehicle 10 described above. This pivoting legmodification may prove to be easier to manufacture for some types ofvehicles.

For the above-described embodiments, it will be appreciated that whilethe body 12 is shown shaped as a sphere, that the body could just asreadily take the shape of a tetrahedron (FIG. 8A), icosahedron (FIG.8B), or other form of polyhedron. The precise shape of the body 12 maydictate how many legs can be used on the body. For example, a pyramid(tetrahedron) shaped body 12′, as shown in FIG. 8A, may permit the useof four legs 14′ (only three being visible), while an icosahedron shapedbody 12″ may permit the use of twelve legs 14″ (one at each of itstwelve vertices). Obviously, the greater the number of legs used, thegreater the degree of precision that will be available in causing thevehicle 10 to follow a desired path. Also, depending on the selectedbody shape, the lengths of the extendable legs 14 may need to beslightly increased or decreased. Generally speaking, the closer theoutward shape of the body 12 is to that of a sphere, the lower theamount of leg thrust needed to cause locomotion of the vehicle.

The various embodiments of the vehicle 10 enable a single actuator to beused to selectively extend virtually any number of independentlyextendable legs. By using a single actuator and a gimbal system toposition the actuation in the various non-parallel planes needed toalign the actuator with different legs, a significant weight savings canbe achieved. The overall complexity of the system may also be reducedthrough the use of only a single actuator. In essence, the greater thenumber of legs employed with the vehicle, the greater the weight andcost savings is likely to become by using only a single actuator.

It will be appreciated that various modifications could be made to thesystem and method described herein without departing from the presentdisclosure. The examples illustrate the various embodiments and are notintended to limit the present disclosure. Therefore, the description andclaims should be interpreted liberally with only such limitation as isnecessary in view of the pertinent prior art.

1. A method for forming a robotic vehicle comprising: forming a bodydefining a volume therewithin; arranging a plurality of extendable legsto project from said body for supporting said body on a surface and forpropelling said body, in at least a partial rolling motion, over saidsurface; supporting a support platform within said body for movementwithin at least two different non-parallel planes; and using an actuatormounted on said support platform to selectively engage said extendablelegs to cause said extendable legs to be extended, to assist in causinga generally rolling motion of said body.
 2. The method of claim 1,wherein said extendable legs are sequentially actuated one at a time. 3.The method of claim 1, wherein supporting a support platform within saidbody for movement within at least two different non-parallel planescomprises using a gimbal system to support said support platform toenable movement of said support platform within more than twonon-parallel planes.
 4. The method of claim 1, wherein arranging aplurality of extendable legs to project from said body comprisesarranging a plurality of extendable legs to project from said body suchthat a coaxial center line of each said extendable leg extends through ageometric center of said body.
 5. The method of claim 1, wherein forminga body comprises forming a body shaped as a sphere.
 6. The method ofclaim 1, wherein forming a body comprises forming a body shaped as apolyhedron.
 7. The method of claim 1, wherein arranging a plurality ofextendable legs comprises arranging a plurality of extendable legs thateach have a biasing element associated therewith for maintaining eachsaid extendable leg in a normally retracted orientation.